The Painter in oil

The height of the lower part of the window should be at least six from the floor,
and for ordinary purposes the proportion of window space to floor space should be
about one-tenth. It is impossible to give a rule; but if the floor is about twelve feet by
sixteen, say, a window about five feet by four will be enough, or six and a half by
three if it is placed horizontally. If you want intense light with strong contrast of
light and shade on your model, have the window smaller and squarer, and place your
easel just under it, where the light is good. The rest of the room will be dark. Better
have the window large enough, and have it so curtained that you can cut off as much
light as you need to. All this is if you are going to make yourself a window; in which
case you will think well before you commit yourself.
More probably you will have to get along as best you can with the ordinary room and
the ordinary window. In which case get a high room with the window running up as
close to the ceiling as possible, and facing north, then you can curtain it so as to
control the light.
Arrangement of Ordinary Windows. - For a good working light you should
have only one window in your room; for the light coming in from two openings will
make a crossing of rays which will not only interfere with the simplicity of the effect
of light and shade on your model, but will make a glaring your canvas. You can either
close the light out of the right-hand window, or, better, arrange a curtain so the light
from one window will not fall on the same place as that from the other.
When you are working from still life or from a model this is often an advantage,
for you can have a strong side-light on the model, and a second light on the canvas.
To arrange this, have a sort of crane made of iron, shaped like a carpenter’s square,
which will swing at right angles with the wall, the arm reaching, say six feet into the
room. Swing this by means of staples well up to the ceiling, so that the light cannot
get over it, and near to the right-hand window. From this arm you can hang a thick,
dark curtain, which will cover and shut out the light from the right-hand window
when swung back over it. If you want to pose your model in the light of that window,
while you paint in that of the other, swing the curtain out into the room at right
angles to the wall, and it will prevent a cross light from the two windows; so that
when the model is posed back of the curtain the light from that window will not fall
on the canvas, nor the light from the other fall on the model.
The light will be best on your picture coming from well above as you work. There
will then be no reflections on the paint. You may find it necessary to cover entirely
the lower half of the window which gives your painting-light. You will find it useful
to have a shade of good solid Holland, arranged with the roller at the bottom, and a
string running up through a pulley at the top; so that you may pull the shade up from
the bottom instead of down from the top, and so cut off as much of the lower part of
the window as is necessary.
If you need the light from the lower part of the window, you may make a thin
curtain of muslin to cover the lower sash, which will let the light through, but diffuse
the rays and prevent reflection.